/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.test.util;

import org.hamcrest.Matcher;
import org.hamcrest.MatcherAssert;
import org.springframework.lang.Nullable;
import org.springframework.util.CollectionUtils;
import org.springframework.util.StringUtils;
import org.springframework.util.xml.SimpleNamespaceContext;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;

import javax.xml.namespace.QName;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import java.io.ByteArrayInputStream;
import java.util.Collections;
import java.util.Map;


/**
 * A helper class for applying assertions via XPath expressions.
 *
 * @author Rossen Stoyanchev
 * @since 3.2
 */
public class XpathExpectationsHelper {

    private final String expression;

    private final XPathExpression xpathExpression;

    private final boolean hasNamespaces;


    /**
     * XpathExpectationsHelper constructor.
     *
     * @param expression the XPath expression
     * @param namespaces the XML namespaces referenced in the XPath expression, or {@code null}
     * @param args       arguments to parameterize the XPath expression with using the
     *                   formatting specifiers defined in {@link String#format(String, Object...)}
     * @throws XPathExpressionException if expression compilation failed
     */
    public XpathExpectationsHelper(String expression, @Nullable Map<String, String> namespaces, Object... args)
            throws XPathExpressionException {

        this.expression = String.format(expression, args);
        this.xpathExpression = compileXpathExpression(this.expression, namespaces);
        this.hasNamespaces = !CollectionUtils.isEmpty(namespaces);
    }

    private static XPathExpression compileXpathExpression(String expression,
                                                          @Nullable Map<String, String> namespaces) throws XPathExpressionException {

        SimpleNamespaceContext namespaceContext = new SimpleNamespaceContext();
        namespaceContext.setBindings(namespaces != null ? namespaces : Collections.emptyMap());
        XPath xpath = XPathFactory.newInstance().newXPath();
        xpath.setNamespaceContext(namespaceContext);
        return xpath.compile(expression);
    }


    /**
     * Return the compiled XPath expression.
     */
    protected XPathExpression getXpathExpression() {
        return this.xpathExpression;
    }


    /**
     * Parse the content, evaluate the XPath expression as a {@link Node},
     * and assert it with the given {@code Matcher<Node>}.
     */
    public void assertNode(byte[] content, @Nullable String encoding, final Matcher<? super Node> matcher)
            throws Exception {

        Node node = evaluateXpath(content, encoding, Node.class);
        MatcherAssert.assertThat("XPath " + this.expression, node, matcher);
    }

    /**
     * Apply the XPath expression and assert the resulting content exists.
     *
     * @throws Exception if content parsing or expression evaluation fails
     */
    public void exists(byte[] content, @Nullable String encoding) throws Exception {
        Node node = evaluateXpath(content, encoding, Node.class);
        AssertionErrors.assertTrue("XPath " + this.expression + " does not exist", node != null);
    }

    /**
     * Apply the XPath expression and assert the resulting content does not exist.
     *
     * @throws Exception if content parsing or expression evaluation fails
     */
    public void doesNotExist(byte[] content, @Nullable String encoding) throws Exception {
        Node node = evaluateXpath(content, encoding, Node.class);
        AssertionErrors.assertTrue("XPath " + this.expression + " exists", node == null);
    }

    /**
     * Apply the XPath expression and assert the resulting content with the
     * given Hamcrest matcher.
     *
     * @throws Exception if content parsing or expression evaluation fails
     */
    public void assertNodeCount(byte[] content, @Nullable String encoding, Matcher<Integer> matcher)
            throws Exception {

        NodeList nodeList = evaluateXpath(content, encoding, NodeList.class);
        String reason = "nodeCount for XPath " + this.expression;
        MatcherAssert.assertThat(reason, nodeList != null ? nodeList.getLength() : 0, matcher);
    }

    /**
     * Apply the XPath expression and assert the resulting content as an integer.
     *
     * @throws Exception if content parsing or expression evaluation fails
     */
    public void assertNodeCount(byte[] content, @Nullable String encoding, int expectedCount) throws Exception {
        NodeList nodeList = evaluateXpath(content, encoding, NodeList.class);
        AssertionErrors.assertEquals("nodeCount for XPath " + this.expression, expectedCount,
                (nodeList != null ? nodeList.getLength() : 0));
    }

    /**
     * Apply the XPath expression and assert the resulting content with the
     * given Hamcrest matcher.
     *
     * @throws Exception if content parsing or expression evaluation fails
     */
    public void assertString(byte[] content, @Nullable String encoding, Matcher<? super String> matcher)
            throws Exception {

        String actual = evaluateXpath(content, encoding, String.class);
        MatcherAssert.assertThat("XPath " + this.expression, actual, matcher);
    }

    /**
     * Apply the XPath expression and assert the resulting content as a String.
     *
     * @throws Exception if content parsing or expression evaluation fails
     */
    public void assertString(byte[] content, @Nullable String encoding, String expectedValue) throws Exception {
        String actual = evaluateXpath(content, encoding, String.class);
        AssertionErrors.assertEquals("XPath " + this.expression, expectedValue, actual);
    }

    /**
     * Apply the XPath expression and assert the resulting content with the
     * given Hamcrest matcher.
     *
     * @throws Exception if content parsing or expression evaluation fails
     */
    public void assertNumber(byte[] content, @Nullable String encoding, Matcher<? super Double> matcher) throws Exception {
        Double actual = evaluateXpath(content, encoding, Double.class);
        MatcherAssert.assertThat("XPath " + this.expression, actual, matcher);
    }

    /**
     * Apply the XPath expression and assert the resulting content as a Double.
     *
     * @throws Exception if content parsing or expression evaluation fails
     */
    public void assertNumber(byte[] content, @Nullable String encoding, Double expectedValue) throws Exception {
        Double actual = evaluateXpath(content, encoding, Double.class);
        AssertionErrors.assertEquals("XPath " + this.expression, expectedValue, actual);
    }

    /**
     * Apply the XPath expression and assert the resulting content as a Boolean.
     *
     * @throws Exception if content parsing or expression evaluation fails
     */
    public void assertBoolean(byte[] content, @Nullable String encoding, boolean expectedValue) throws Exception {
        String actual = evaluateXpath(content, encoding, String.class);
        AssertionErrors.assertEquals("XPath " + this.expression, expectedValue, Boolean.parseBoolean(actual));
    }

    /**
     * Evaluate the XPath and return the resulting value.
     *
     * @param content     the content to evaluate against
     * @param encoding    the encoding to use (optionally)
     * @param targetClass the target class, one of Number, String, Boolean,
     *                    org.w3c.Node, or NodeList
     * @throws Exception if content parsing or expression evaluation fails
     * @since 5.1
     */
    @Nullable
    public <T> T evaluateXpath(byte[] content, @Nullable String encoding, Class<T> targetClass) throws Exception {
        Document document = parseXmlByteArray(content, encoding);
        return evaluateXpath(document, toQName(targetClass), targetClass);
    }

    /**
     * Parse the given XML content to a {@link Document}.
     *
     * @param xml      the content to parse
     * @param encoding optional content encoding, if provided as metadata (e.g. in HTTP headers)
     * @return the parsed document
     */
    protected Document parseXmlByteArray(byte[] xml, @Nullable String encoding) throws Exception {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        factory.setNamespaceAware(this.hasNamespaces);
        DocumentBuilder documentBuilder = factory.newDocumentBuilder();
        InputSource inputSource = new InputSource(new ByteArrayInputStream(xml));
        if (StringUtils.hasText(encoding)) {
            inputSource.setEncoding(encoding);
        }
        return documentBuilder.parse(inputSource);
    }

    /**
     * Apply the XPath expression to given document.
     *
     * @throws XPathExpressionException if expression evaluation failed
     */
    @SuppressWarnings("unchecked")
    @Nullable
    protected <T> T evaluateXpath(Document document, QName evaluationType, Class<T> expectedClass)
            throws XPathExpressionException {

        return (T) getXpathExpression().evaluate(document, evaluationType);
    }

    private <T> QName toQName(Class<T> expectedClass) {
        QName evaluationType;
        if (Number.class.isAssignableFrom(expectedClass)) {
            evaluationType = XPathConstants.NUMBER;
        } else if (CharSequence.class.isAssignableFrom(expectedClass)) {
            evaluationType = XPathConstants.STRING;
        } else if (Boolean.class.isAssignableFrom(expectedClass)) {
            evaluationType = XPathConstants.BOOLEAN;
        } else if (Node.class.isAssignableFrom(expectedClass)) {
            evaluationType = XPathConstants.NODE;
        } else if (NodeList.class.isAssignableFrom(expectedClass)) {
            evaluationType = XPathConstants.NODESET;
        } else {
            throw new IllegalArgumentException("Unexpected target class " + expectedClass + ". " +
                    "Supported: numbers, strings, boolean, and org.w3c.Node and NodeList");
        }
        return evaluationType;
    }

}
